In the case of supervised problem domains, you implicitly make a decision about what is signal, and what is noise, and sure, in that closed setting, supervised learning is much more sample efficient. But I think what we're learning now is that with strong enough base models, 'aha' moments in RL training show that it might be possible to essentially 'squeeze out signal from language itself', giving you far greater breadth of latent knowledge than supervised examples, and letting you train to generalize to far greater horizons than a fixed dataset might allow. In a fascinating way it is rather reminiscent of, well, abiogenesis. This might sound like speculative claptrap if you look at the things the current generation of models are still weak at, but... there's a real chance that there is a very heavy tail to the set of outcomes in the limit.